A data network switch permits data communication among a plurality of media stations in a local area network. Data frames, or packets, are transferred between stations by means of data network switch media access control (MAC). The network switch passes data frames received from a transmitting station to a destination station based on the header information in the received data frame.
Packet transmission events typically are tracked to provide a basis for statistical analysis of network operation with respect to each data network switch port. For example, the number of transmitted packets, received packets, transmission collisions and the like can be counted and polled periodically. These significant parameters, termed objects, are collected in a Management Information Base (MIB). Through the use of statistical counters, determination can be made of improper device operation such as, for example, loss of packets.
Conventionally, each MAC unit includes internal counters of limited capacity for counting a small number of MIB objects. Flip-flops are incremented each time an item is changed. The counted objects are output to readable registers, then to be appended to data packets in a MAC transmit operation. The increased MAC complexity owing to these components, coupled with the relatively limited MIB reporting functionality for this scheme, are significant disadvantages. Later versions provide a RAM based memory on the switch logic chip as a full counter for MIB data received from all of the MACs on the chip. Incorporation of a large capacity RAM in the switch logic chip to accommodate MIB data objects from all ports incurs undesirable expense. As the number of poled MIB objects increases to keep up with expanding statistical requirements, available RAM capacity must meet these needs. Space constraints inherent in the integration of the various elements on a single logic chip impose additional disadvantages.